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regulator: fix memory leak on error path of regulator_register() 

The change corrects registration and deregistration on error path
of a regulator, the problem was manifested by a reported memory
leak on deferred probe:

    as3722-regulator as3722-regulator: regulator 13 register failed -517

    # cat /sys/kernel/debug/kmemleak
    unreferenced object 0xecc43740 (size 64):
      comm "swapper/0", pid 1, jiffies 4294937640 (age 712.880s)
      hex dump (first 32 bytes):
        72 65 67 75 6c 61 74 6f 72 2e 32 34 00 5a 5a 5a  regulator.24.ZZZ
        5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a  ZZZZZZZZZZZZZZZZ
      backtrace:
        [<0c4c3d1c>] __kmalloc_track_caller+0x15c/0x2c0
        [<40c0ad48>] kvasprintf+0x64/0xd4
        [<109abd29>] kvasprintf_const+0x70/0x84
        [<c4215946>] kobject_set_name_vargs+0x34/0xa8
        [<62282ea2>] dev_set_name+0x40/0x64
        [<a39b6757>] regulator_register+0x3a4/0x1344
        [<16a9543f>] devm_regulator_register+0x4c/0x84
        [<51a4c6a1>] as3722_regulator_probe+0x294/0x754
        ...

The memory leak problem was introduced as a side ef another fix in
regulator_register() error path, I believe that the proper fix is
to decouple device_register() function into its two compounds and
initialize a struct device before assigning any values to its fields
and then using it before actual registration of a device happens.

This lets to call put_device() safely after initialization, and, since
now a release callback is called, kfree(rdev->constraints) shall be
removed to exclude a double free condition.

Fixes: a3cde9534e ("regulator: core: fix regulator_register() error paths to properly release rdev")
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Cc: Wen Yang <wenyang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20200724005013.23278-1-vz@mleia.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Vladimir Zapolskiy 2020-07-24 03:50:13 +03:00 committed by Mark Brown
parent 2ca76b3e49
commit 9177514ce3
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 7 additions and 11 deletions
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18
drivers/regulator/core.c
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@ -5092,7 +5092,6 @@ regulator_register(const struct regulator_desc *regulator_desc,
struct regulator_dev *rdev;
bool dangling_cfg_gpiod = false;
bool dangling_of_gpiod = false;
bool reg_device_fail = false;
struct device *dev;
int ret, i;
@ -5221,10 +5220,12 @@ regulator_register(const struct regulator_desc *regulator_desc,
}
/* register with sysfs */
device_initialize(&rdev->dev);
rdev->dev.class = &regulator_class;
rdev->dev.parent = dev;
dev_set_name(&rdev->dev, "regulator.%lu",
(unsigned long) atomic_inc_return(&regulator_no));
dev_set_drvdata(&rdev->dev, rdev);
/* set regulator constraints */
if (init_data)
@ -5275,12 +5276,9 @@ regulator_register(const struct regulator_desc *regulator_desc,
!rdev->desc->fixed_uV)
rdev->is_switch = true;
dev_set_drvdata(&rdev->dev, rdev);
ret = device_register(&rdev->dev);
if (ret != 0) {
reg_device_fail = true;
ret = device_add(&rdev->dev);
if (ret != 0)
goto unset_supplies;
}
rdev_init_debugfs(rdev);
@ -5302,17 +5300,15 @@ unset_supplies:
mutex_unlock(&regulator_list_mutex);
wash:
kfree(rdev->coupling_desc.coupled_rdevs);
kfree(rdev->constraints);
mutex_lock(&regulator_list_mutex);
regulator_ena_gpio_free(rdev);
mutex_unlock(&regulator_list_mutex);
put_device(&rdev->dev);
rdev = NULL;
clean:
if (dangling_of_gpiod)
gpiod_put(config->ena_gpiod);
if (reg_device_fail)
put_device(&rdev->dev);
else
kfree(rdev);
kfree(rdev);
kfree(config);
rinse:
if (dangling_cfg_gpiod)